This challenge is a mystery - uncover the rules and details by completing the daily puzzles!

Rules:

One crew member must be someone who didn't have their own Challenge during the month (3 points earned if your entry follows this rule)

312 and 1/2 combined with the number of 19 is the Grand Challenge's renown requirement, only counting the renown from your main resource (3 Points earned if your entry follows this rule)

You are required to collect Campaign as your main resource in your Grand Challenge submission. (3 points earned if your entry follows this)

You are required to collect a Treasure which matches the first, but not the second part of the puzzle for Puzzle 22 - any [spoiler]Mask Treasure that can be worn - but not the Benin Mask[/spoiler] (3 Points earned if your entry follows this)

Additional Rule added for a bonus 5 points to complete - with your submission, include the name of who first set this challenge (in full)! (Note: This rule does not count towards medal requirements, just towards point requirements)

You must play on Adventure mode.

(Find out the hidden rules by completing the puzzles from the first 23 days)

Scoring:

Each rule followed successfully will earn you 3 points, and each individual puzzle you post the correct answer for awards 1 point, and may offer bonus points if offered for that puzzle.

BRONZE: 14 points and at least 1 hidden rule followed (4MP*)

SILVER: 18 points and at least 2 hidden rules followed (8MP*)

GOLD: 20 points and at least 3 hidden rules followed (12MP*)

PLATINUM: 25 points and a submission that follows all four hidden rules for the grand challenge (12MP+**)

* Number of medal points awarded when playing on Classic Difficulty. Easy and Normal give less, according to these rules. Bear in mind that the rules described do apply for Easy/Normal submissions, but multiply those rewards by 4 for their proper values for this month.
** The platinum medal is extraordinary and can only be achieved on Classic or Impossible difficulty without losing. It doesn't increase Medal Points further than a Gold medal, but we will track how many you have.

How to participate
You can participate with a highscore, helping with the individual puzzles, a story or any/all of these.

Highscores
Play the game according to the challenge rules (As far as possible) and in Adventure mode.
Post in this topic a screenshot of your Win Screen*, right after the ceremony or your Leaderboard record.*
Submit by 12:00 noon CET, (03/01/17) (Or 01/03/17 for those using MM/DD/YY)
(click here for your local time equivalent)
NOTE: Only one score will be accepted - only one submission for each player please. If you wish to enter a new score, please edit your initial entry and make it clear which score you are submitting, and add the word "EditGreenlight" to the entry so we can see immediately when the result needs updating.
*If you forget to screenshot the Win screen, you can also enter with a screenshot of your Leaderboards: Go to Main Menu > Leaderboards > Local > click the entry that matches your submission game > screenshot those details.

For the 27th, players have an option to select from - visit the link and add your vote there: 27th's Options for community to select (Deadline 13.00 noon 28th, needs 3+ majority or will carry over to the next day)